This invention relates to patient monitoring systems, and, more particularly, to the use of bidirectional communication between a sensor unit and a monitor unit.
Advances in sensor technology, electronics, and communications have made it possible for physiological characteristics of patients to be monitored even when the patients are ambulatory and not in continuous, direct contact with a hospital monitoring system. For example, U.S. Pat. No. 5,959,529 describes a monitoring system having a remote monitoring unit in which a monitor unit receives the sensor output of a sensor unit that is associated with the patient. The sensor unit and the monitor unit are preferably linked by a wireless communication path. The remote monitoring unit monitors one or more physiological characteristics of the patient according to the medical problem of the patient, such as the heartbeat and its waveform. Under selected conditions, the remote monitoring unit communicates with a central unit to provide data to the central unit and to receive programming, instructions, and medical instructions from the central unit.
The monitoring system of the ""529 patent and other monitoring systems, while operable, offer the opportunity for improvement and optimization of the performance of the systems. The present invention provides such an improvement and optimization for remote patient monitoring systems.
The present invention provides a monitoring system and a method for its use. The monitoring system retains the basic architecture of a remote monitoring unit having a sensor unit and a monitor unit, which in turn may communicate with a central unit. The performance of the system achieves improved communications performance between the sensor unit and the monitor unit.
In accordance with the invention, a monitoring system comprises a remote monitoring unit having a sensor unit, which in turn comprises a sensor having a sensor output, a sensor bidirectional local transceiver that receives the sensor output, and a sensor unit processor in communication with the sensor unit bidirectional local transceiver. The remote monitoring unit further comprises a monitor unit having a monitor unit bidirectional local transceiver that supports bidirectional wireless communications with the sensor bidirectional local transceiver, a monitor unit processor in communication with the monitor unit bidirectional local transceiver, and a monitor unit bidirectional remote transceiver in communication with the monitor unit processor. The monitoring system may further include a central unit comprising a central unit bidirectional remote transceiver supporting bidirectional communications with the monitor unit bidirectional remote transceiver, and a central unit processor in communication with the central unit bidirectional remote transceiver.
A key feature of the monitoring system is that it transmits information bidirectionally between the sensor unit and the monitor unit. The sensor unit is conventionally viewed as having only a transmitter to transmit information to the monitor unit. However, substantial improvements in system performance as well as user convenience result from bidirectional communication between the sensor unit and the monitor unit.
For example, it is possible that information transmitted from the sensor unit to the monitor unit is corrupted in some fashion. Corruption detection techniques may be employed by the monitor unit. The monitor unit transmits a retransmit signal to the sensor unit in the event that the information is corrupted, and the sensor unit may retransmit the information to the monitor unit until uncorrupted information is received at the monitor unit.
In another case, the monitor unit determines a signal strength of the information transmitted from the sensor unit to the monitor unit. The monitor unit may then transmit a distance warning signal to the sensor unit that the patient is straying too far from the monitor unit. The monitor unit may also send a signal-strength signal to the sensor unit so that the power output of the sensor unit may be adjusted as required under the circumstances so that no more battery power is consumed than is necessary.
In yet another situation, the sensor unit may transmit information to the monitor unit at a first frequency, and the monitor unit determines whether the signal is adversely affected by frequency-dependent interference. The monitor unit transmits a frequency-change signal to the sensor unit in the event that the information is adversely affected by frequency-dependent interference, so that the sensor unit may transmit further information to the monitor unit at a second frequency.
The monitor unit may also transmit a warning signal to the sensor unit to signal the patient to take action such as replacing a battery, viewing a message, visiting the monitor unit, and so on.
Thus, in the present approach the sensor unit is not viewed simply as a transmit-only device, which senses a physiological or other condition, converts the sensed value to an electrical signal, and then transmits the electrical signal to the monitor unit. Instead, the quality of the information received at the monitor unit and the performance of the local transceiver system may be controlled with communications back to the sensor system, and other information may be communicated to the patient through the sensor unit.
Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. The scope of the invention is not, however, limited to this preferred embodiment.